Thermostatic control device and system utilizing the same

ABSTRACT

A coiled tube having opposed ends one of which being interconnected to a frame means and the other being movable relative thereto and being interconnected to a temperature sensing bulb whereby expansion and contraction of the fluid in the bulb causes movement of the other end of the tube relative to the frame means. A pair of switch blades are carried by the frame means and normally are moved toward each other for electrical contact therebetween. Control means is carried by the frame means for selectively adjusting the position of one of the switch blades relative to the frame means. The other end of the tube carries means for engaging against the other of the blades to cause movement thereof in a direction away from the one blade when a certain temperature is sensed by the bulb whereby the setting of the control means determines the sensed temperature that will cause the tube to open the switch blades.

[ May 23, 1972 United States atent Hild etal.

[5 4] THERMOSTATIC CONTROL DEVICE FOREIGN PATENTS OR APPLICATIONS ANDSYSTEM UTILIZING THE SAME [72] lnventors: Henry F. Hild; Siegfried E.Manecke;

697,182 9/1953 GreatBritain...;.....................337/322 1,054,3534/1959 'Germany..............................73/368.6

James L. Shaw, all of Indiana, Pa.

Primary Examiner-Hemard A. Gilheany Robertshaw Controls p y, AssistantExaminerDewitt M. Morgan Richmond, Va Attorney-Auzville Jackson, Jr.,Robert L. Marben and Canoct. 7, 1970 dor, Candor & Tassone I [21] Appl.No.: 78,737 [57] [22] Filed:

ABSTRACT A coiled tube having opposed ends one of which being inter-[52] U.S. C1....

connected to a frame means and the other being movable relative theretoand being interconnected to a temperature sensing bulb whereby expansionand contraction of the fluid in the bulb causes movement of the otherend of the tube relative to the frame means. A pair of switch blades arecarried by the frame means and normally are moved toward each other for32 9 24% 3 1 nhwnad 3 9 Z. 0H6 B 3 8 3 72 t 3/ 2 3 3 2 937 3 2m... 2 0 1B 5 2 a 3, a n n 3 1 l 3 0 l 3 9 0 3 .0 "3 .l 7 3 m3 m2 1 m 3 1 "ms 0mam I MZ d m he. 1.] 8 55 [.l

References Cited electrical contact therebetween. Control means iscarried by the frame means for selectively adjusting the position of oneof UNITED STATES PATENTS the switch blades relative to the frame means.The other end 10/1918 Hadaway ofthe tube carries means for engagingagainst the other of the 294 10/1930 Schlaich...

337/306 X blades to cause movement thereof in a direction away from""337/322 X the one blade when a certain temperature is sensed by the""219/496 bulb whereby the setting of the control means determines the12 sensed temperature that will cause the tube to open the switch....2l9/4l2 blades ......337/323 Lang........ 26 Claims, 8 DrawingFigures 506 4/1959 Jordan..... 969 7/196l Alcott...... 235 11/1968 Hildet al..... 123 3/1971 Wolfe et all 091 4/1958 a s 9 1 v 7 v.

v t i v i 1 y Patented May 23, 1972 3,665,362

3 Sheets-Sheet 1 75 INVENTORS.

76 HENRY F. HILD SIEGFRIED E. MANECKE BY JAMES L. SHAW THEIR ATTORNEYSPatented May 23, 1972 3 Sheets-Sheet THEIR ATTORNEYS SIEGFRIED E.MANECKE JAMES L.SHAW

duh 6.44 M

F I 6 HENRY F. EI XS vTIIERMOS'IATIC CONTROL DEVICE AND SYSTEM UTILIZINGTHE SAME This invention relates to a thermostatic control device for anoven or the like as well as to an improved control system utilizing sucha thermostatic control device or the like.

It is well known that various thermostatic control devices have beenprovided for ovens to permit the user to select a desired cookingtemperature as well as a hightemperature burn-off cleaning operating.However, such prior known thermostatic devices usually utilize twodifferent temperature responsive means respectively for controlling thenormal cooking operation and the high temperature burn-off cleaningoperation.

One of the features of this invention is to provide a thermostaticcontrol device that can be utilized for controlling both the normalcooking operations of a domestic oven or the like as well as the hightemperature burn-off cleaning operations thereof with such controldevice utilizing only one temperature responsive means for controllingboth operations.

Another feature of this invention is to provide such a thermostaticcontrol device which can be utilized for any number of desired purposes,such as for only a normal cooking operation-a nd the like.

- In particular, one embodiment of the thermostatic control device ofthis invention comprises a frame means carrying a coiled tube that hasopposed ends one of which is interconnected to the frame means and theother is movable relative thereto, the coiled tube having a temperaturesensing bulb interconnected thereto whereby expansion and contraction offluid in the bulb causes movement of the other end of the tube relativeto the frame means. A pair of switch blades are carried by the framemeans and normally are moved toward each other for electrical contacttherebetween for interconnecting an electrical power source toelectrical heating means of a domestic oven or the like. Control meansare carried by the frame means for selectively adjusting the position ofone of the switch blades relative to the frame means'for selecting acooking operation of the heating means. The other end of the tubecarries means for engaging against the other of the blades to causemovement thereof in a direction away from the one blade when a certaintemperature is sensed by the bulb whereby the setting of the controlmeans determines the sensed temperature that will cause the tube to openthe switch blades and, thus, maintain the output temperature effect ofthe heating means in the oven at the temperature etfect selected by thecontrol means.

Such a thermostatic device can be utilized in an oven controlsystemwherein other switch blades thereof control other operations of theoven, such as a high temperature burn-off cleaning operation, door lockconstruction, low temperature operations, etc., with the tubecontrolling such other pairs of switch blades in the manner previouslydescribed.

Accordingly, it is an object of this invention to provide an improvedthermostatic control device having one or more of the novel features ofthis invention asset forth above or hereinafter shown or described.

Another object of this invention is to provide an improved controlsystem utilizing such a thermostatic device or the like.

'Other objects, uses or advantages of this invention are apparent from areading of this description which proceeds with reference to theaccompanying drawings forming a part thereof and wherein:

FIG. 1 is a fragmentary, front view of a cooking apparatus carrying thethermostatic control device of this invention.

FIG. 2 is an enlarged view of the thermostatic control device of FIG. 1with the control knob thereof removed.

FIG. 3 is a view similar to FIG. 2 of the control device of thisinvention with the cover thereof removed.

FIG. 4 is a cross-sectional view of the thermostatic device of FIG. 2and is taken on line 4--4 thereof.

FIG. v5 is a reduced view of the rear of the thermostatic device of FIG.2.

FIG. 6 is an exploded perspective view of the various parts of thethermostatic device of FIG. 2.

FIG; 7 is a fragmentary cross-sectional view taken substantially on line7-7 of FIG. 3.

FIG. 8 is a schematic view illustrating the improved oven control systemof this invention.

While the various features of this invention are hereinafter describedand illustrated as being particularly adapted to control the cooking andhigh temperature bum-off cleaning operations of a domestic oven or thelike, it is to be understood that the various features of this inventioncan be utilized singly or in any combination thereof to provide controlmeans for other apparatus as desired.

Therefore, this invention is not to be limited to only the embodimentillustrated in the drawings, because the drawings are merely utilized toillustrate one of the wide'variety of uses of this invention.

Referring now to FIGS. 1-7, the improved thermostatic control device ofthis invention is generally indicated by the reference numeral 10 andcomprises a housing or frame means 11 formed from a front plate 12, arear plate 13 and a central housing member 14 having opposed open endsI5 and 16 respectively closed by the plates 12 and 13 that are adaptedto be secured thereto by threaded fastening members 17 as illustrated.The front plate 12 has a pair of cars or tangs 18 adapted to extend overthe central member 14 at corner recesses 19 thereof to secure the upperportion of the front plate 12 to the central member 14 while the lowerend of the front plate 12 is secured to the central member 14 by thethreaded fastening members 17 being received in threaded openings 20 ofthe central member 14. The rear plate 13 is secured to the centralmember 14 by the two threaded fastening members 17 likewise beingreceived in threaded openings (not shown) in the central member 14.

The plates 12 and 13 cooperate with the central member 14 to define achamber 21 in the frame means or housing means I l which is adapted toreceive a coiled tube 22 of this invention.

The coiled tube 22 has an outer end 23 adapted to be secured to the rearplate 13, such as by'spot welding thereto, and has an inner end 24disposed within the spiral or coil and being adapted to be movedrelative to the frame means 11 upon the expansion and contraction offluid contained within the tube 22 and interconnected to a temperaturesensing bulb 25 by a capillary tube 26. Since the control device 10of'this invention is adapted :6 control a high temperature burn-offcleaning operation which takes place with the temperature being aroundl'-,000 F., the bulb 26 and tube 22 are filled with helium so that thesame can withstand and accurately control the high temperature operationas well as the low temperature cooking operation as will be apparenthereinafter.

The movable end or inner end 24 of the tube 22 has opposed sides 27 and28 respectively provided with outwardly directed pivot pins 29 that arerespectively secured in suitable openings 30 of a pair of legs 31 and 32of a U-shaped member 33 that has the legs 31 and 32thereof completelystraddling the coiled tube 22 with the cross member 34 thereof extendingacross the top of the coiled tube 22 in spaced relation relative theretowhereby expansion and contraction of the fluid in the bulb 25 and tube22 causes the coiled tube 22 to tend to unwind or'to wind up and therebycause a back and forth rocking motion of the U-shaped member 33 relativeto the frame means 11.

An electrically insulating cross bar 35 is secured to the cross member34 of the U member 33 by an S-shaped member 36 suitably riveted to thecross bar member 35 by rivets 37 and to the cross member 34 of the Umember 33 by rivets 38. The S- shaped member 36 is made from a bimetaland serves to provide ambient compensation for the coil tube 22.

In order to initially fill the temperature sensing bulb 25 and tube 22with the aforementioned helium, a fill conduit means 39 is disposed influid communication with the tube 22 in parallel relation to thecapillary tube26 as illustrated in FIG. 6 whereby helium can be forcedinto the tube 22 and, thus, into the bulb 25 until the same have beenfilled to the desired degree whereby the filled tube 39 can besubsequently sealed closed in any desired manner.

The capillary tube 26 and the fill conduit means 39 are held in placeagainst the outer surface of plate 13 by the clamp means 9. The clampmeans 9 is held in place by the threaded fastening members 17 used tosecure plate 13 to member 14.

The front plate 12 of the thermostatic device carries an internallythreaded bushing 40 which threadedly receives an externally threadedmember 41 that is secured to a C-shaped control shaft 42 that is adaptedto project through a suitable opening in the oven frame structure 43 asillustrated in FIG. 1 so as to receive a control knob 44 thereon forrotating the shaft 42 and, thus, rotating the externally threaded member41 relative to the frame means 11 so as to cause axial movement of thethreaded member 41 within the stationary threaded bushing 40. Theexternally threaded member 41 has an open-' ing 45 passing axiallytherethrough with the left hand portion 46 thereof being internallythreaded to threadedly receive an adjusting screw 47 that has an end 47disposed within the right hand unthreaded portion of the bore 45 to abutagainst an electrically insulating pin or rod 48 that has the positionof its-free end 49 in the chamber 21 of the frame means 11 adjusted bythe axial adjustment of the threaded member 41 within the stationarythreaded portion 40 as will be apparent hereinafter.

A bracket member 50 is secured to the internally threaded bushing 40 andhas opposed ears 51 and 52 provided with openings 53 for fastening thecontrol device 10 to the desired structure, such as the frame structure43 of a domestic oven or the like, such as the control panel thereof asillustrated in FIG. 1'. The bracket 50 has inwardly bent tangs 54utilized as a stop means for the rotation of the control shaft 42because the control shaft 42 carries a disc 55 having an outwardlydirected tang 56 which engages against the top side of the tang 54 ofthe bracket 50 in the manner illustrated in FIGS. 2 and 6 when thecontrol shaft 42 is disposed in its off position and against the underside of the tang 54 when the control shaft 42 is set in its highesttemperature position.

Thus, it can be seen that when the control shaft 42 is disposed in itsoff position as illustrated in FIGS. 2 and 6, the rod or pin 48controlled thereby projects into the chamber 21 of the housing means 11to its greater extent and when the control knob 44 as illustrated inFIG. 1 is rotated in a clockwise direction from its off position asillustrated to its higher temperature position, the threaded member 41is axially moved to the left in F l0. 4 whereby the pin 48 will be inits least projected condition into the chamber 21 of the housing means]1 for a purpose hereinafter described.

In order to provide tension or feel" for the location of the shaft 42relative to the control device 10, a bowed leaf spring 57 is disposedbetween the bracket member 50 and the plate 55 of the control shaft 42whereby rotation of the control shaft 42 relative to the frame means 11is opposed by the friction provided by the bowed leaf spring 57 toprovide the aforementioned feel for the rotation of the control knob 44relative to the control panel 43.

A pair of switch blades 58 and 59 are carried by the frame means 11 andare adapted to cooperate together at free ends 60 and 61 thereof, wheresuitable contact means 62 and 63 are secured, for completing anelectrical circuit therebetween. The upper switch blade 58 is bestillustrated in FIG. 3 and comprises a substantially rectangular portion64 having a rectangular cutout 65 therein and carrying a bent tang 66extending rearwardly from a top portion 67 thereof to be insertedbetween a back wall 68 of the central housing member 14 and a U-shapedsleeve portion 69 of a terminal 70 to secure the end 66 of the switchblade 58 to the frame means 11 while the lower end 60 thereof is adaptedto move relative to the frame means 11 about the hinge portion 67 of theswitch blade 58 in a manner hereinafter described. The terminal 70 isadapted to project through a slot 71 in the rear wall 68 of the centralhousing member 14 to extend outwardly from the same to be interconnectedto a suitable electrical lead in a manner hereinafter described whilethe U-shaped portion 69 thereof has an inner portion 72 received inasuitable slot 73 formed in the rear wall 68 of the central housingmember 14, the terminal being staked in place in the slot 71 of the wall68 by suitable staking 74 as illustrated in FIG. 4. Thus, when the tang66 of the switch blade 58 is assembled into the slot means formedbetween the U-shaped portion 69 of the terminal 70 and the rear wall 68of the frame means 11 as illustrated in FIG. 3, the same can be spotwelded together so as to provide positive securement and positiveelectrical connection between the terminal 70 and the switch blade 58.

The contact portion 62 of the'switch blade 58 is offset to the right asillustrated in FIG. 3 to cooperate with the free end 61 of the switchblade 59 which also has its lower end 75 secured to the housing means 11by a U-shaped portion 69A of another terminal 76 of the control device10 in a manner similar to the terminal 70.

The switch blade 59 has a natural resiliency or bias that tends tomovethe movable end'6l thereof toward the switch blade 58 as illustratedin FIG. 4 and a compression spring 77' is disposed between the rear wall68 of the central housing member 14 and the switch blade 58 to tend tomove the switch blade 58 toward the switch blade 59 whereby the switchblade 58 and 59 are normally placing the electrical contacts 62 and 63thereof together.

The cross bar 35 of the tube 22 of the control device 10 is disposed insuch a position that the same is adapted to engage against the switchblade 59 below the switch blade 58 to move the same in a direction awayfrom the switch blade 58 to tend to separate the switch blades 59 and 58upon an increase in temperature sensed by the bulb 25 as the expansionof fluid in the tube 22 tends to unwind the same. However, the switchblade 58 tends to follow such movement of the switch blade 59 becausethe force of the compression spring 77' is tending to move the switchblade 58 to the left in FIG. 4.

However, the position of the pin 48 under the influence of the settingof the control knob 44 limits the amount of movement of the switch blade58 to the left in FIG. 4 as the end 49 of the pin 48 is in thepath ofmovementof the switch blade 58. Therefore, it can be seen that thesetting of the control knob 44 to a desired temperature setting willcause the switch blades 58 and 59 to remain in electrical contact witheach other as long as the temperature sensed by the bulb 25 is below theset temperature of the knob 44 andwill cause opening of the switchblades 58 and 59 when the temperature sensing bulb 25 senses atemperature above the temperature set by the control knob 44. In thismanner, the pair of switch blades 58 and 59 are adapted to controlthe-normal cooking operation of a domestic oven or the like as will beapparent hereinafter. l

' Another pair of switch blades 77 and 78 are carried by the frame means11 by respectively having opposed ends 79 and 80 thereof secured toU-shaped portions 693 and 69C of terminals 81 and 82 so that free ends83 and 84 thereof are adapted to cooperate together to provide anelectrical circuit between the terminals 81 and 82 when the blades 77and 78 are in electrical contact with each other at the free ends 83 and84 thereof. However, the lower blade 78 is in the path of movement ofthe cross bar, 35 of the tube 22 so that at a certain sensedtemperature, the cross bar 35 will move the switch blade 78 away fromthe switch blade 77 because the natural bias of the switch blade 78 istoward the switch blade 77 and the position of the switch blade 77relative to the housing means 14 is controlled by a set screw 85disposed in a threaded bore 86 in the rear wall 68 of the centralhousing member 14 with the natural bias of the switch blade 77 beingtoward the rear wall 68 of the housing member 14. Thus, depending uponthe setting of the set screw 85, the opening and closing of the switchblades 77 and 78 will take place at a certain sensed temperature wherebysuch pair of switch blades 77 and 78 are adapted to control anon-cooking and warmthretaining temperature operation for the oven ofthe cooking apparatus 43 in a manner hereinafter described.

Another. pair of switch blades 87 and 88 are carried by the frame means11 with the switch blades 87 and 88 respectively having ends 89 and90secured to the frame means 11 by the U-shaped portions 69D and 69E ofterminals 91 and 92 whereby the free ends 93 and 94 of the switchblades'87 and 88 are adapted to cooperate together to provide electricalcircuit between the terminals 91 and 92. However, the switch blade88 isdisposed in the path of movement of the cross bar 35 of the tube 22'sothat the natural bias of the switch blade 88 toward the switch blade 87can be overcome by movement of thecross bar 35'away from the switchblade 87 to open the circuit between the switch blades 87 and 88 when acertain temperature is sensed by the temperature sensing bulb 25, theswitch blade 87 having a natural bias toward the end wall 68 and havingits position set by the set screw 85A in the same manner as the setscrew 85 previously described. The switch blades 87 and 88 are adaptedto control a high temperature burn-off cleaning operation of the cookingapparatus 43 in a manner hereinafter described.

Another pair of switch blades95 and 96 are carried by the frame meansllby having the ends 97 and 98 thereof respectively secured to the rearwall 68 of the central housing member 14 by the U portions 69F and 69Gof terminals 99 and 100'whereby the free ends 101 and 102 of the switchblades 95 and 96 are adapted to cooperate together to provide anelectrical circuit between the terminals 99 and 100. However, the crossbar 35 is disposed to engage the switch blade 96 and movethe same awayfrom the switch blade 95 upon a temperature sensed by the bulb 25reaching a certain temperatureto overcome the natural bias of the switchblade 96 toward the switch blade 95, the switch blade 95 having anatural bias toward the rear wall 68 of the central housing member 14and having its position adjusted thereto by the set screw 85D, FIG: 5,in a manner similar to the set screw 85. The switch blades 95 and 96 areadapted to provide a door locking function during a cleaning operationof the cooking apparatus 43 as will be apparent hereinafter.

Therefore, it can be seen that the tube 22, through its insulatingcontact bar 35,'is adapted to control the operation of the four pairs ofswitch blades 58, 59; 77, 78; 87, 88; and 95, 96 with each pair ofswitch blades being opened and closed at different temperatures sensedby the sensing bulb 25 to provide an automatic control system for thecooking apparatus 43 now to be described. j As illustratedin FIG. 8, animproved control system of this invention is generally indicated by thereference numeral 103 and comprises a pair of power source leads L, andL for operating a'bake heating element 104 and a broil heating element105 of the cooking apparatus 43. The power source lead L is adapted tobe interconnected to the side 106 of the bake element 104 or the side107 of the broil element 105 by suitable selector switching means 108depending upon whether the switching means 108 is set for a bakingoperation or a broiling operation. Likewise, the power source lead L isadapted to be interconnected to both the bake element 104 and the broilelement 105 when the switching means 108 sets forth a bumoff cleaningoperation.

The control device of this invention is schematically illustrated bydash lines in FIG. 8 and comprises the main cycling or moving switchblade 59 and its cooperable and adjustable switch blade 58, the movableswitch blade 78 and its cooperable and adjustable switch blade 77, themovable switch blade 88 and its cooperable and adjustable switch blade87 and the movable switch blade 96 and its cooperable and adjustableswitch blade 95 interconnected into the control system 103 asillustrated in FIG. 8.

In particular, the movable switch blade 59 is electricallyinterconnected by its terminal 76 to a lead 109 that is interconnectedto the power source lead L,, the adjustable switch blade 58 beinginterconnected through its terminal 70 to a lead 110 that isinterconnected to a timer operated switch blade 111. The timer operatedswitch blade 111 is adapted to be closed against a fixed contact 112which is interconnected by a lead 113 to the terminal of the movableswitch blade 88.

The lead is also interconnected by a lead 114 to the terminal 82 of themovable switch blade 78 while the adjustable switch blade 77 isinterconnected by its terminal 81 to a lead 1 15 that is interconnectedto the lead 113. The adjustable switch blade 87 is interconnected by itsterminal 91 to a lead 116 thatis interconnected to one side 117 of asmall heater element 118 of a thermal relay switch 119. The; other side120 of the heater element 118 is interconnected by a lead 121 to thepower source lead L The thermal relay switch 119 has .a movable switchblade 122 formed by bimetallic material which is adapted to closeagainst a fixed contact 123 when the heater element 118 is operating soas to interconnect the lead 121 to a lead 124 interconnected to thefixed contact 123 at one end thereof and to the side 125 of the bakeelement 104' at the other end thereof.

The side 120 of the heating element 1 18 of the thermal relay switch 119is also interconnected by a lead 126 to one side 127 of a heatingelement 128 ofanother thermal relay switch 129, the side 127 of theheating element 128 also being interconnected to the side 1 17 ofthe-heatingelement 118 by a lead 130. The other side 131 of the heatingelement 128 is interconnected to the power source lead L The thermalrelay switch 129 has its bimetal switch blade 132 movable against afixed contact 133 that is interconnected to the side 134 of the broilelement 105 by a lead 135, the switch blade 132 only closing against thecontact 133 when the heating element 128 is energized.

The cooking apparatus 103 is provided with a movable switch blade 136which is interconnected to the lead L, by a lead 137 and is normallydisposed in an open condition relative to a fixed contact 138 as long asthe manual latch member for the oven door is in its unlatched orunlocked position. However, when such oven door latch member is moved toits latching position, the same closes the switch blade 136 against thefixed contact 138 which is interconnected to the selector switchingmeans 108. The selector switch 108, when positioned in the cleanposition for the bum-off cleaning cycles connects the fixed contact 138to lead 1 10.

The movable blade 96 of the thermostatic device 10 is interconnected byits terminal 100 to a lead 140 which is interconnected to a fixedcontact 141 that cooperates with a normally opened switch blade 142 thatis interconnected to the power source lead L by a lead 143. Theadjustable switch blade 95 of the thermostatic device 10 isinterconnected by its terminal 99 to a lead 144 that is interconnectedto one side 145 of a solenoid coil 146 that has its other side 147interconnected by a lead 148 to ground. The solenoid coil 146 whenenergized is adapted to move a latching pin out of latching engagementwith the manual door latch lever so that the door latch lever can bemoved from its unlatching position to its locking position or can bemoved from its locking position to its unlatching position, bothoperations of the door latch member only taking place when the coil 146is energized as will be apparent hereinafter.

The operation of the control system 103 will now be described.

Assuming that the housewife or the like desires to utilize the controlsystem 103 for a conventional baking operation of the cooking apparatus43, the selector means 108 is set for a baking operation so that thepower source lead L is only interconnected to the side 106 of the bakeelement 104; Since the timer is in a manual position thereof the switchblade 11 1 is disposed in its closed position against the contact 112.The housewife sets the control knob 44 at the desired cookingtemperature whereby as long as the temperature in the oven is below theset cooking temperature of a knob 44, the switch blade 59 will bedisposed against the switch blade 58 and since the switch blade 88 forthe high temperature bum-off cleaning operation is always disposedagainst the switch blade 87 until the oven temperature exceeds thebum-off cleaning temperature, the power source lead L, is interconnectedto the heater 118 of the thermal relay switch 119 so that the heater 118is placed across the power source leads l and L The thus operatingheating element 118 heats the bimetal switch blade 122 to move the sameto a closed position against the contact 123 to interconnect the powersource lead 1.. to the side 125 of thebake element 104 so that the bakeelement 104 is placed across the power source leads L, and L to heat theoven to the desired baking temperature at which time the switch blade 59is moved away from the switch blade 58 to disconnect the heater 118 fromacross the power source leads L, and L and, thus, cause the switch blade122 to move to its open position to disconnect the element 104 fromacross the power source leads L, and L,..

In this manner, the switch blade 59 is cycled between its open aridclosed positions to tend to maintain the temperature in the oven at thebaking temperature selected by the selector knobv 44. g

Such a baking operation could be an automatically timed baking operationwhereby after the lapse of a selected baking time period, the controldevice will maintain the oven at a low, non-cooking and warmth-retainingtemperature until the housewife or the like desires to remove the foodfrom the oven.

' In particular, after the previously described baking operation hastaken place from the predetermined time period, the timer clock causesthe switch blade 111 to move away from the fixed contact 112 to its openposition as illustrated in FIG. 8 whereby the onlytime the power sourcelead L, can be interconnected to the lead 113 to operate the thermalswitch 119 is when the switch blade 78 is disposed against theswitchblade 77 andthe switch blade 78 is only moved against the switch blade77 when the temperature in the oven has fallen just below a non-cookingand warmth-retaining temperature, such as a l70 F., and, of course, atsuch low temperature, the

switch blade 59 is disposed against the'switch blade 58 whereby thecycling of the switch blade 78 between its open and closed positionswill maintain the temperature in the oven at a low temperature as set bythe set screw 85.

When the system 103 is utilized for a broiling operation, the selectorswitch 108 is moved toa "broil position thereof with the control knob 44also being moved to its broiling position (approximately 625 F.) so thatthe broil element 105 will be placed across the power source leads L,and 1. when the switch blade 1320f the thermal relay 129 is moved to itsclosed position by the heater element 128 being placed across the powersource leads L, and L in the same manner as the heating element 118 forthe thermal relay switch 119 for the bake element 104 as previouslydescribed, the switch blade 59 cycling between its open and closedpositions to maintain the broiling temperature in the oven in the samemanner as the previously described baking operation.

When the housewife or the like desires to utilize the control system 103for a high temperature burn-off cleaning operation, the selector switch108 is placed in the clean" position, the control knob 44 turned to theoven clean position thereof, and the timer (not shown) for controllingswitch blade 111 is set so blade 1 11 is in contact with contact 112 forthe desired burn-ofi period. The housewife or the like must alsomomentarily close the switch 142 which energizes the solenoid 146 byplacing the same across the power source leads L, and ground since theswitch blade 96 is normally maintained against the switch blade 95 untilthe temperature of the oven exceeds'550 F. or the like. Energizing ofthe solenoid coil 146 will movethe locking pin so that the housewife cannow move the oven door latch member from its unlocked position to itslocked position. With the oven door latch member now being disposed inits locked position, the switch blade 136 is closed against the fixedcontact 138 connecting the power source lead L, to the selector switchmeans'l08. The oven door is therefore locked before the selector switch108 when placed in the clean position is effective to connect the powersource lead L, to the timer operated switch blade 111. The housewifereleases the button 142 after the door latch member has been moved toits locked position which will cause deenergizing of the coil 146 sothat the latch pin now drops into place to hold the door latch member inits locked position until the coil 146 is again energized which, ofcourse, cannot take place unless the oven temperature is below 550 F.because when the oven temperature is above 550 F., the contact bar 35 ofthe tube 22 has moved the switch blade 96 away from the switch blade 95so that thecoil 146 cannot be energized at any time when the oven isabove 550 F. I

With the switch blade 136 now disposed against contact 138 with the ovenlatch member in its locked position, the switch blade 88 remains againstthe contact 87 to interconnect the power source lead L, to the heaters118 and 128 of the thermal relay switches 119 and 129 to cause theheating elements 104 and 105 to be placed across power source leads L,and L, to heat the oven to the high temperature for burn-off purposeswhich temperature when reached in the oven will cause the contact bar 35to move against the switch blade 88 and move the same away from thefixed blade 87 to turn oh the elements 104 and 105 until the oven againfalls below such high temperature setting of the set screw A. Thus, theswitch blade 88 will be cycled between its open and closed position bythe tube 22 to maintain the temperature at the high burn-off cleaningtemperature.

The cleaning operation is terminated when the switch 111 opens uponcompletion of the selected bum-off time or by operation of the selectorswitch 108 to the foff" position which prevents the elements 104' and105 from having the sides 106 and 107 thereof interconnected to thepower source leads L,, the temperature in the oven begins to drop andwhen the same falls below 550 F., the switch blade 96 is again permittedto close against the switch blade by. the contacting tube 22 so that thehousewife or the like can again close the switch 142 to energize thecoil 146 and retract the latching pin so that the oven door latch membercan be moved from its locked position to its unlocked which will openthe switch blade 136 away from the contact 138. v I

' Therefore, it can be seen that the coiled tube 22 of the thermostaticdevice 10 of this invention is a'dapted to control the various pairs ofswitches in the control device 10 for not only the normalcookingoperation of the cooking apparatus 43, but also for the cleaningoperation thereof.

' However, it is to be understood that if it is desired to utilize thethermostatic device 10 for an ovenfthat'does not provide for a cleaningoperation thereof, only the pair of switch blades 59 and 58 of thedevice 10 need be utilized. Alternatively, the switch blades 59, 58 and78, 77 can be utilized without the oven door latch means 96, 95 and hightemperature clean-off operations 88, 87, as desired.

Accordingly, it can be seen that this invention not only provides animproved thermostatic control'device having many novel and unobviousfeatures, but also this invention provides an improved control systemfor an oven or the like.

While the form of the invention now preferred has been disclosed asrequired by the statutes, other forms may be used, all coming within thescope of the claims which follow.

What is claimed is:

1. A thermostatic device comprising frame means, a coiled tube havingopposed ends one of which is interconnected to said frame means and theother being movable relative thereto, a temperature sensing bulbinterconnected to said tube whereby expansion and contractionof fluid insaid bulb causes movement of said other end of said tube relative tosaid frame means, a pair of switch blades carried by said frame meansand normally being moved toward each other for electrical contacttherebetween, control means carried by said frame means for selectivelyadjusting the position of one of said switch blades relative to saidframe means, and means carried by said other end of said tube forengaging against the other of said blades to cause movement thereof in adirection away from said one blade when a certain temperature is sensedby said bulb whereby the setting of said control means determines thesensed temperature that will cause said tube to open said switch blades,said tube being ribbon-like with opposed side edges and being coiledinto a spiral with said other end thereof being an inner end of saidspiral, said means carried by said other-end of said tube comprising aU-shaped member having the legs thereof interconnected to said opposedside edge of said other end ofsaid tube.

2. A thermostatic device as set forth in claim 1 wherein an engagementbar is carried by the cross member of said U- shaped member for'engagingagainst said other switch blade.

3. A thermostatic device as set forth in claim 2 wherein said engagementbar is formed of electrical insulating material.

4. A thermostatic device as set forth in claim 1 wherein said one switchblade has opposed ends, one of said ends of said one switch blade beingsecured to said frame means and the other end thereof being movablerelative to said frame means and carrying contact means for electricallycontacting said other switch blade.

5. Athermostatic device as set forth in claim 4 wherein a compressionspring is disposed between said frame means and said one switch blade totend to move said other end thereof toward said other switch blade. 7

6. A thermostatic device as set forth in claim 5 wherein said controlmeans comprises an axially movable member carried by said frame meansand engageable with said one switch blade on the side thereofopposite tothe compression spring engaged side thereof to set the position of saidone blade relative to said frame means. i

7. A thermostatic device as set forth in claim 6 wherein said controlmeans comprises a rotatable member threaded to said frame means, saidaxially movable member being disposed between said rotatable member andsaid one switch blade.

8. A thermostatic device as set forth in claim 7 wherein said axiallymovable member comprises a pin formed of electrically insulatingmaterial.

9. A thermostatic device as set forth in claim 1 wherein another pair ofswitch blades is carried by said frame means and normally being movedtoward each other for electrical contact therebetweemsaid means carriedby said other end of said tube being adapted to engage against one ofsaid blades of said other pair thereof and move the same away from theother blade of said pair thereof when a certain temperature is sensed bysaid bulb. 7

10. A thermostatic device as set forth in claim 9 wherein said framemeans carries an adjusting member to adjust the position of said oneblade of said other pair thereof relative to said frame meansto changethe temperature that must 'be sensed by said bulb before said other pairof switch blades will open.

11. A thermostatic device as set forth in claim 10 wherein said switchblades of said other pair thereof each has opposed ends one of which issecured to said frame means and the other being movable relative thereoffor cooperating with the movable end of the other blade of said pair.

12. A thermostatic device as set forth in claim 11 wherein said framemeans carries a pair of slot means respectively receiving said one endsof said switch blades of said other pair to secure the same to saidframe means.

13. A thermostatic device as set forth in claim 1 wherein a plurality ofother pairs of switch blades are carried by said frame means and arenormally being moved toward each other for electrical contacttherebetween, said means carried by said other end of said tube beingadapted to engage against one of said blades of each other pair thereofand move the same away from the other blade of said pair thereof when acertain temperature is sensed by said bulb. r

14. In an oven control system having a heating means, the improvementcomprising a thermostatic device having frame means, a coiled tubehaving opposed ends one of which is interconnected to said frame meansand the other being movable relative thereto, a temperature sensing bulbdisposed to sense the temperature effect in said oven and beinginterconnected to said tube whereby expansion and contraction of fluidin said bulb causes movement of said other end of said tube relative tosaid frame means, a pair of switch blades carried by said frame meansand normally being moved toward each other for electrical contacttherebetween, said switch blades being operatively interconnected withsaid heating means for operating said heating means when said switchblades are in contact with each other, control means carried by saidframe means for selectively adjusting the position of one of saidswitchblades relative to said framemeans, and means carried by saidother end of said tube for engaging against the other of said blades tocause movement thereof in a direction away from said one blade when acertain temperature is sensed by said bulb whereby the setting of saidcontrol means determines the sensed temperature that will cause saidtube to open said switch blades and, thus, the temperature of said oven,said tube being ribbon-like with opposed side edges and being coiledinto a spiral with said other end thereof being an inner end of saidspiral, said means carried by said other end of said tube comprising aU-shaped member having the legs thereof interconnected to said opposedside edges of said other end of said tube.

15. In an oven control system as set forth in claim 14 the furtherimprovement wherein an engagement bar is carried by the cross member ofsaid J-shaped member for engaging against said other switch blade.

16. In an oven control system as set forth in claim 15 the furtherimprovement wherein said engagement bar is formed of electricalinsulating material.

17. In an oven control system as set forth in claim 14 the furtherimprovement wherein said one switch blade has opposed ends, one of saidends of said one switch blade being secured to said frame means and theother end thereof being movable relative to said frame means andcarrying contact means for electrically contacting said other switchblade.

18. In an oven control system as set forth in claim 17 the furtherimprovement wherein a compression spring is disposed between said framemeans and said one switch blade to tend to move said other end thereoftoward said other switch blade.

19. In an oven control system as set forth in claim 18 the furtherimprovement wherein said control means comprises an axially movablemember carried by said frame means and engageable with said one switchblade on the side thereof opposite to the compression spring engagedside thereof to set the position of said one blade relative to saidframe means.

20. In an oven control system as set forth in claim 19 the furtherimprovement wherein said control means comprises a rotatable memberthreaded to said frame means, said axially movable member being disposedbetween said rotatable member and said one switch blade.

21. In an oven control system as set forth in claim 20 the furtherimprovement wherein said axially movable member comprises a pin formedof electrically insulating material.

22. In an oven control system as set forth in claim 14 the furtherimprovement wherein another pair of switch blades is carried by saidframe means and are normally being moved toward each other forelectrical contact therebetween, said means carried by said other end ofsaid tube being adapted to engage against one of said blades of saidother pair thereof and move the same away from the other blade of saidpair thereof when a certain temperature is sensed by said bulb.

23. In an oven control system as set forth in claim 22 the furtherimprovement wherein said frame means carries an adjusting member toadjust the position of said one blade of said other pair thereofrelative to said frame means to change the temperature that must besensed by said bulb before said other pair of switch blades will open.

24. In an oven control system as set forth in claim 23-the furtherimprovement wherein said switch blades of said other pair thereof eachhas opposed ends one of which is secured to said frame means and theother being movable relative thereof for cooperating with the movableend of the other blade of said pair.

mally being moved toward each other for electrical contact therebetweensaid means carried by said other end of said tube being adapted toengage against one of said blades of each other pair thereof and movethe'same away from the other blade of said pair thereof when a certaintemperature is sensed by said bulb.

# I I I

1. A thermostatic device comprising frame means, a coiled tube havingopposed ends one of which is interconnected to said frame means and theother being movable relative thereto, a temperature sensing bulbinterconnected to said tube whereby expansion and contraction of fluidin said bulb causes movement of said other end of said tube relative tosaid frame means, a pair of switch blades carried by said frame meansand normally being moved toward each other for electrical contacttherebetween, control means carried by said frame means for selectivelyadjusting the position of one of said switch blades relative to saidframe means, and means carried by said other end of said tube forengaging against the other of said blades to cause movement thereof in adirection away from said one blade when a certain temperature is sensedby said bulb whereby the setting of said control means determines thesensed temperature that will cAuse said tube to open said switch blades,said tube being ribbon-like with opposed side edges and being coiledinto a spiral with said other end thereof being an inner end of saidspiral, said means carried by said other end of said tube comprising aU-shaped member having the legs thereof interconnected to said opposedside edge of said other end of said tube.
 2. A thermostatic device asset forth in claim 1 wherein an engagement bar is carried by the crossmember of said U-shaped member for engaging against said other switchblade.
 3. A thermostatic device as set forth in claim 2 wherein saidengagement bar is formed of electrical insulating material.
 4. Athermostatic device as set forth in claim 1 wherein said one switchblade has opposed ends, one of said ends of said one switch blade beingsecured to said frame means and the other end thereof being movablerelative to said frame means and carrying contact means for electricallycontacting said other switch blade.
 5. A thermostatic device as setforth in claim 4 wherein a compression spring is disposed between saidframe means and said one switch blade to tend to move said other endthereof toward said other switch blade.
 6. A thermostatic device as setforth in claim 5 wherein said control means comprises an axially movablemember carried by said frame means and engageable with said one switchblade on the side thereof opposite to the compression spring engagedside thereof to set the position of said one blade relative to saidframe means.
 7. A thermostatic device as set forth in claim 6 whereinsaid control means comprises a rotatable member threaded to said framemeans, said axially movable member being disposed between said rotatablemember and said one switch blade.
 8. A thermostatic device as set forthin claim 7 wherein said axially movable member comprises a pin formed ofelectrically insulating material.
 9. A thermostatic device as set forthin claim 1 wherein another pair of switch blades is carried by saidframe means and normally being moved toward each other for electricalcontact therebetween, said means carried by said other end of said tubebeing adapted to engage against one of said blades of said other pairthereof and move the same away from the other blade of said pair thereofwhen a certain temperature is sensed by said bulb.
 10. A thermostaticdevice as set forth in claim 9 wherein said frame means carries anadjusting member to adjust the position of said one blade of said otherpair thereof relative to said frame means to change the temperature thatmust be sensed by said bulb before said other pair of switch blades willopen.
 11. A thermostatic device as set forth in claim 10 wherein saidswitch blades of said other pair thereof each has opposed ends one ofwhich is secured to said frame means and the other being movablerelative thereof for cooperating with the movable end of the other bladeof said pair.
 12. A thermostatic device as set forth in claim 11 whereinsaid frame means carries a pair of slot means respectively receivingsaid one ends of said switch blades of said other pair to secure thesame to said frame means.
 13. A thermostatic device as set forth inclaim 1 wherein a plurality of other pairs of switch blades are carriedby said frame means and are normally being moved toward each other forelectrical contact therebetween, said means carried by said other end ofsaid tube being adapted to engage against one of said blades of eachother pair thereof and move the same away from the other blade of saidpair thereof when a certain temperature is sensed by said bulb.
 14. Inan oven control system having a heating means, the improvementcomprising a thermostatic device having frame means, a coiled tubehaving opposed ends one of which is interconnected to said frame meansand the other being movable relative thereto, a temperature sensing bulbdisposed to sense the temperature effect in said oven and beinginterconnected to said tube Whereby expansion and contraction of fluidin said bulb causes movement of said other end of said tube relative tosaid frame means, a pair of switch blades carried by said frame meansand normally being moved toward each other for electrical contacttherebetween, said switch blades being operatively interconnected withsaid heating means for operating said heating means when said switchblades are in contact with each other, control means carried by saidframe means for selectively adjusting the position of one of said switchblades relative to said frame means, and means carried by said other endof said tube for engaging against the other of said blades to causemovement thereof in a direction away from said one blade when a certaintemperature is sensed by said bulb whereby the setting of said controlmeans determines the sensed temperature that will cause said tube toopen said switch blades and, thus, the temperature of said oven, saidtube being ribbon-like with opposed side edges and being coiled into aspiral with said other end thereof being an inner end of said spiral,said means carried by said other end of said tube comprising a U-shapedmember having the legs thereof interconnected to said opposed side edgesof said other end of said tube.
 15. In an oven control system as setforth in claim 14 the further improvement wherein an engagement bar iscarried by the cross member of said U-shaped member for engaging againstsaid other switch blade.
 16. In an oven control system as set forth inclaim 15 the further improvement wherein said engagement bar is formedof electrical insulating material.
 17. In an oven control system as setforth in claim 14 the further improvement wherein said one switch bladehas opposed ends, one of said ends of said one switch blade beingsecured to said frame means and the other end thereof being movablerelative to said frame means and carrying contact means for electricallycontacting said other switch blade.
 18. In an oven control system as setforth in claim 17 the further improvement wherein a compression springis disposed between said frame means and said one switch blade to tendto move said other end thereof toward said other switch blade.
 19. In anoven control system as set forth in claim 18 the further improvementwherein said control means comprises an axially movable member carriedby said frame means and engageable with said one switch blade on theside thereof opposite to the compression spring engaged side thereof toset the position of said one blade relative to said frame means.
 20. Inan oven control system as set forth in claim 19 the further improvementwherein said control means comprises a rotatable member threaded to saidframe means, said axially movable member being disposed between saidrotatable member and said one switch blade.
 21. In an oven controlsystem as set forth in claim 20 the further improvement wherein saidaxially movable member comprises a pin formed of electrically insulatingmaterial.
 22. In an oven control system as set forth in claim 14 thefurther improvement wherein another pair of switch blades is carried bysaid frame means and are normally being moved toward each other forelectrical contact therebetween, said means carried by said other end ofsaid tube being adapted to engage against one of said blades of saidother pair thereof and move the same away from the other blade of saidpair thereof when a certain temperature is sensed by said bulb.
 23. Inan oven control system as set forth in claim 22 the further improvementwherein said frame means carries an adjusting member to adjust theposition of said one blade of said other pair thereof relative to saidframe means to change the temperature that must be sensed by said bulbbefore said other pair of switch blades will open.
 24. In an ovencontrol system as set forth in claim 23 the further improvement whereinsaid switch blades of said other pair thereof each has opposed ends oneof which is secured to saiD frame means and the other being movablerelative thereof for cooperating with the movable end of the other bladeof said pair.
 25. In an oven control system as set forth in claim 24 thefurther improvement wherein said frame means carries a pair of slotmeans respectively receiving said one ends of said switch blades of saidother pair to secure the same to said frame means.
 26. In an ovencontrol system as set forth in claim 14 the further improvement whereina plurality of other pairs of switch blades are carried by said framemeans and are normally being moved toward each other for electricalcontact therebetween, said means carried by said other end of said tubebeing adapted to engage against one of said blades of each other pairthereof and move the same away from the other blade of said pair thereofwhen a certain temperature is sensed by said bulb.